FIG. 1 depicts a portion of conventional head 1 including a conventional perpendicular magnetic recording (PMR) transducer 10 and conventional read transducer 40 separated by an insulator 6, as viewed from the air-bearing surface (ABS). For clarity, the conventional PMR transducer 10 is not drawn to scale. Also depicted is the substrate 2, which may be part of a body of a slider (not separately depicted in FIG. 1). The conventional PMR transducer 10 includes a conventional first pole 12, alumina insulating layer 14, alumina underlayer 16 that may be considered part of the alumina insulating layer 14, conventional PMR pole 18 that typically includes a seed layer (not shown), insulating layer 20, shield gap 26, top shield 28, and insulating layer 30. Note that in certain other embodiments, the top shield 28 may also act as pole during writing using the conventional PMR transducer 10. The conventional PMR pole 18 and the top shield 80 are surrounded by insulating layers 20 and 30, respectively. The conventional PMR pole 18 has sidewalls that, for generality, are depicted including segments 22A and 22B and segments 24A and 24B, respectively. In addition, in some cases, the conventional PMR pole 18 may have footings 23 and 25.
In conventional applications, the height of the conventional PMR pole 18 is typically less than approximately three-tenths micrometer. The conventional PMR pole 18 also has a negative angle such that the top of the conventional PMR pole 18 is wider than the bottom of the conventional PMR pole 18. Stated differently, the angle θ of the sidewalls is less than 90 degrees in the conventional PMR pole 18 of FIG. 1. A pole having this height and shape is desirable for use in PMR applications.
FIG. 2 is a flow chart depicting a conventional method 50 for fabricating the conventional PMR transducer 10 using a damascene process. For simplicity, some steps are omitted. The conventional method 50 is described in the context of the conventional PMR head 1. The conventional method 10 starts after formation of the first pole 12 and the alumina 14. The alumina underlayer 16 and insulating layer 20 are formed. Thus, the insulating layers 14, 16, and 20 may be part of a single, larger insulating layer. A mask is formed, via step 52. The mask is typically a reactive ion etch (RIE) mask having an aperture that is the same width as the top of the conventional PMR pole 18. A RIE is performed to form a trench in the insulating layer 20, via step 54. The trench in the insulating layer 20 has substantially the same shape as the conventional PMR pole 18. The trench is refilled using the material for the conventional PMR pole 18, via step 56. The mask formed in step 52 may be removed, via step 58. The material may be planarized, via step 60. Consequently, the conventional PMR pole 18 remains. Fabrication of the PMR head 1 is then completed, via step 62.
The conventional method 50 may result in a conventional PMR pole 18 in which the sidewalls are substantially linear. For example, the sidewalls are depicted as being formed of two line segments 22A and 22B that are not linear and segments 24A and 24B that are not linear. When using the method 50, the segments 22A and 22B form a single line and the segments 24A and 24B form a single line. In addition, footings 23 and 25 are typically not present.
Although the conventional method 50 may be used to fabricate the conventional PMR pole 18, there are drawbacks. For example, the changes in the length of the RIE performed in step 54 results in varying thicknesses of the trench. Consequently, the height of the conventional PMR pole 18 may vary. Such a variation between conventional PMR poles 18 is undesirable.
Alternatively, the conventional PMR pole 18 may be formed using a mill-and-lap process. FIG. 3 depicts a conventional method 70 for forming the conventional PMR transducer 10 using a mill-and-lap process. For simplicity, some steps are omitted. The high magnetic moment material for the conventional PMR pole 18 is deposited, via step 72. A chemical mechanical planarization (CMP) stop layer and hard mask layer are deposited, via step 74. A seed layer is deposited, via step 76. A resist pattern for the hard mask layer is formed on the seed layer, via step 78. Step 78 typically includes providing a layer of photoresist and patterning the layer to provide the desired mask. The ion milling mask is plated and the photoresist removed, via step 80. Thus, the ion milling mask is used to mask the desired portions of the high moment material to be used to form the conventional PMR pole 18. The PMR pole material is milled, via step 82. Consequently, the width of the conventional PMR pole 18 and the negative angle are set in step 82. The insulator 20 is deposited around the conventional PMR pole 18, via step 84. A CMP is performed to planarize the surface and expose the conventional PMR pole 18, via step 86. The surface is planarized in order to allow subsequent processing to be performed as desired. The shield gap 26 is provided, via step 88. The top shield 28 is deposited and patterned in step 90. Finally, the region around the top shield 28 is insulated, via step 92.
Although the conventional method 70 can be used to form a conventional PMR transducer 10, the process utilized to trim the conventional PMR pole 18 results in artifacts which adversely affect the functioning of the conventional PMR transducer 10. In particular, the sidewalls of the conventional PMR pole 18 may include one or more angles. Such a condition, in which each segments 22A and 22B and segments 24A and 24B are not linear, is depicted in FIG. 1. The desired profile of the conventional PMR pole 18 is a trapezoid. Consequently, such nonuniformities in the sidewalls 22 and 24 are undesirable. In addition, footings 23 and 25 may be present at the base of the conventional PMR pole 18. The footings 23 and 25 are composed of the material(s) used in forming the pole. Other artifacts may include increased roughness of the sidewalls 22 and 24 as well as redeposition of the pole material being trimmed. These artifacts of the pole trim are generally undesirable.
Accordingly, what is needed is an improved method for fabricating a PMR head.